1. Field of the Invention
The present invention relates to a side-view type light emitting device, in particular, to a side-view type light emitting device in which heat generated on the substrate surface is transmitted to a back side of the substrate via a through hole.
2. Description of the Related Art
A side-view type light emitting device in which heat generated on a substrate surface is transmitted to a back side of the substrate via a through-hole has been proposed in Japanese Laid-Open Patent Publication TOKUKAI No. 2003-78176. This related art type of LED is depicted in FIG. 4. That is, the side-view type light emitting device has a construction in which “ . . . two or more LED elements (37,38,39) each having different emission color are mounted on the surface of the substrate (40), . . . each cathode of each LED element (37,38,39) is electrically connected with a common terminal electrode (41a, 41b) via one of two through holes provided in the substrate (40), . . . each anode of each LED element (37,38,39) is electrically connected respectively to a terminal electrode for anode (42,43,44) via an Au wire . . . ”.
In this related art side-view type light emitting device, “the anode of the LED element (37) and the terminal electrode for anode (42) are electrically connected, and similarly, the anode of the LED element (38) and the terminal electrode for anode (43), and the anode of the LED element (39) and the terminal electrode for anode (44) are electrically connected respectively”.
According to Japanese Laid-Open Patent Publication TOKUKAI No. 2003-78176, deterioration of the LED elements caused by heat can be reduced by using the above-described side-view type light emitting device.
However, in this related art side-view type light emitting device, both the common terminal electrodes (41a, 41b) and the terminal electrode for anode (43) are provided on the rear side of the substrate (40), so that the common terminal electrodes (41a,41b) and the terminal electrode for anode (43) may be accidentally connected through a connecting member such as a solder during the mounting process and short-circuiting occurs.
Therefore, in a related art side-view type light emitting device, it has been necessary to provide a certain margin between the common terminal electrodes (41a, 41b) and the electrode for anode (43). Consequently, there have been problems in a conventional side-view type light emitting device. Miniaturization of the device has been difficult to realize; and the area of the common terminal electrodes (41a,41b) each connected to the respective through hole can not be widened, so that heat generated on the surface of the substrate can not be transmitted to the back side of the substrate effectively in such a device.